Nowadays, due to beautiful metal texture, a mobile terminal with metal frame gets more and more popular. However, the metal frame surrounding the antenna can significantly restrain the radiation of the antenna, thus increasing the difficulty for designing such mobile terminal.
For the 4G mobile terminal, in the related art, there are two main solutions currently applied in the diversity antenna, the GPS (Global Positioning System) antenna, and the BT (Bluetooth) & WLAN (Wireless Local Area Network) antenna.
The first solution refers to a traditional solution, i.e. by using FPC (Flexible Printed Circuit) or LDS (Laser Direct Structuring) production process, the antenna is disposed on an isolated plastic bracket or plastic shell. The antenna testing of this solution has no essential difference with that of the traditional mobile terminal with nonmetal frame. The metal frame is used as a part of the antenna ground, meanwhile a gap of about 0.8 mm˜1 mm is provided at a proper position of the metal frame, and the ground point of the metal frame is optimized, thus reducing the influence of the metal frame on the antenna testing and the performance of the mobile terminal.
The second solution is that the metal frame is divided into several segments by the gaps and the ground point, and is directly fed, meanwhile the PWB (Printed Wiring Board) is provided with the traditional circuit to obtain the performance and the resonant frequency of the antenna.
The first solution has following disadvantages. By using the traditional design and traditional production process, the cost is high; and what is more, the metal frame cannot be integrated with the antenna, which causes a poor RF performance for the antenna.
The second solution has disadvantages of difficulty on the antenna testing. Because the segmentalized metal frame is directly fed to be the antenna, when the size of the metal frame mismatches the resonance and the radiation of the antenna, it is difficult to perform a manual testing (because it is difficult to enlarge or shorten the size of the metal frame manually), and the production period will be prolonged and the expense will be increased if a new mold is required to be prepared or the old mould is required to be modified.